DIY LED Grow Light for Microgreens: Parts, Cost and Step-by-Step Build
How do you build a DIY LED grow light for microgreens? Mount around 30 one-watt LEDs on a 1 m aluminum profile, wire them in series and power the chain with a constant-current LED driver, for example a 350 mA driver with a 28-100 V output. That gives a lamp of about 30 W, the lower end of the 30-60 W we recommend for a 1 m shelf. The LEDs, the driver and the profile cost roughly €40-105, depending on where you buy them.
If you grow microgreens and struggle to find a good LED lamp, you're not alone. Many of the lamps we tested from different suppliers did not meet our expectations, so we went back to the simple DIY lamp we used years ago in our own production. It is simple, repairable and easy to build. Below you will find the parts list with prices, how to match the driver to your LEDs, the step-by-step assembly and, if you would rather not solder, how to set up a shelf with ready-made LED grow light bars. These are the two ways to make a grow light for microgreens: build the lamp from parts, or build the shelf and use ready-made bars.
Table of Contents
1. Why We Built Our Own LED Lamp
Many ready-made lamps looked promising, but in practice they failed: weak light, uneven coverage, overheating drivers, poor build quality or unstable batches. Many of them were also overpriced for such a simple construction. For microgreens, light must be predictable: losing trays because a lamp dies mid-cycle is expensive.
Our old DIY setup turned out more reliable than many of the "professional" lamps we tested. It is simple, repairable and gives stable results. When one LED fails, you replace one LED, not the whole lamp.
If you want to better understand how different LED light types and spectra affect microgreens growth, yield and micronutrient content, we covered this topic in detail here: 📚 Impact of Different LED Light Types on Microgreens Cultivation
Or, if you do not want to build the lamp yourself, choose our ready-made full spectrum LED grow light.
2. DIY LED Grow Light Parts: What You Need
A DIY LED grow light needs four parts: 1 W LEDs on star boards, a constant-current driver, insulated wire and a 1 m aluminum profile, plus heat-shrink tubing to insulate every joint. All of them are easy to find in electronics shops.
Power supply (driver)
A constant-current LED driver. It converts 230 V mains power into a stable current for the LEDs. For LEDs wired in series this is the right type: the driver keeps the current fixed and adjusts its output voltage to the chain. A constant-voltage power supply (12 V or 24 V) is meant for LED strips with built-in resistors, not for a chain of bare LEDs. Choose the driver by two numbers: its current must match the LEDs (350 mA for 1 W LEDs) and its output voltage range must cover the voltage of the whole chain (section 3 shows how to calculate it).
LED modules on PCB
Individual LEDs mounted on small aluminum PCB "stars". They are easy to wire, easy to replace and transfer heat well. We used a mix of cool white (5000-6500 K), red, blue and ultraviolet LEDs. The example in this guide uses 24 white and 6 deep red LEDs, because their voltages are easy to check in the specifications. Our LED study shows how these colors affect microgreens, if you want to adjust the mix.
Wiring
Simple insulated wires. All LEDs are connected in series, which keeps the current equal and the light stable.
Aluminum profile (heat sink)
LEDs need cooling. Use a C-channel (U-channel) aluminum profile, 3-5 mm thick. It spreads heat and protects the lifespan of the LEDs.
Optional but useful: thermal paste or thermal pads, small adhesive clips and a timer for the plug.
The table below lists the parts for a lamp of about 30 W, with the example parts and prices we found in German online shops in October 2026.
3. How It Works
Power supply
The driver keeps the current stable. Check three things on its label: the output type (constant current), the current rating and the output voltage range. Example: if one LED is 1 W and you use 30 LEDs, the total power of the lamp is about 30 W, so the driver must be rated for that, with a safety margin. A 35 W driver for a 30 W lamp is a good match.
Series connection
Power flows through each LED in one line: driver + to LED1 +, LED1 – to LED2 +, and so on, until the – of the last LED goes back to driver –. The same current flows through every LED, which keeps the brightness stable and makes repairs easy.
In a series chain the voltages of the LEDs add up. A white 1 W LED needs about 3.2 V and a deep red one about 2.5 V, so a chain of 24 white and 6 red LEDs needs about 24 x 3.2 + 6 x 2.5 = 92 V. That fits inside the 28-100 V range of a driver like the APC-35-350, and at 350 mA the LEDs draw about 32 W. Thirty white LEDs alone would need 90-102 V (3.0-3.4 V each), which can exceed the 100 V limit. If you want more LEDs, split them into two chains with two drivers, or choose a driver with a higher voltage range. Take the exact voltages from the specification of the LEDs you buy.
Because the chain runs at around 90 V DC, every joint must be insulated. Treat the lamp like any other mains-powered device.
Heat management
The aluminum profile acts as a radiator. It spreads heat, prevents overheating and keeps the light output stable. The thicker the aluminum, the better the cooling.
4. How Much Does a DIY LED Grow Light Cost?
A DIY lamp is not expensive, but it is usually not cheaper than a ready-made bar either. The table compares the parts of the 30 W example lamp with our ready-made 33 W bar, using prices from October 2026 (our prices include Polish VAT).
So why build one? Because you choose the colors yourself, you can repair every part, and you learn how your light works. If what you want is simply light over your trays, a ready-made bar costs about the same or less and saves you the soldering. We have not measured how much light our DIY lamp gives compared with the bar, so compare them by price and convenience, not by light output.
5. Step-by-Step Assembly
The build has five stages: plan the LED layout, mount the LEDs on the profile for cooling, wire them in series, connect the driver and test the lamp. Each step below explains what to do and why it matters. You need basic soldering skills. If you have never worked with mains wiring, have the 230 V side checked by a qualified electrician, or choose ready-made bars (section 6).
1. Prepare all components
Lay out everything on a clean workspace:
- LED modules
- power supply
- aluminum profile
- wires
- screwdriver, soldering iron (or connectors), thermal paste
2. Mark the positions of the LEDs
Place the LED modules along the aluminum profile to check spacing.
Tips:
- keep equal distance between LEDs for even light
- leave space on one end for wiring and the driver input
- avoid placing LEDs too close to the edges
Mark each position lightly with a pencil.
3. Apply thermal paste
Before mounting, clean and degrease the aluminum surface, then add a thin layer of thermal paste or place a thermal pad under each LED module.
This improves heat transfer, which:
- keeps LEDs cool
- increases lifespan
Even cheap LEDs work better with proper cooling.
4. Mount the LEDs on the profile
Fix each LED module to the aluminum profile using screws or strong thermal adhesive.
Make sure all modules sit flat. Any gap reduces heat transfer.
5. Wire the LEDs in series
Use short insulated wires to connect the minus (–) of the first LED to the plus (+) of the second, the minus of the second to the plus of the third, and so on, until all LEDs form one chain. The plus of the first LED and the minus of the last LED stay free for the driver.
Things to check:
- solder joints must be clean and solid
- wires should not touch the aluminum directly without insulation
- keep wiring tidy so nothing overheats
Series wiring keeps the same current through every LED.
6. Connect the driver
Connect the positive output (+) of the driver to the plus of the first LED, and the negative output (–) to the minus of the last LED.
Then connect the driver input to the power cable (230 V). If you add an on/off switch, place it on the input side.
Safety notes:
- double-check polarity
- secure wires with heat-shrink
- mount the driver in a dry, ventilated place, away from where you water the trays
A stable driver is the main protection for your LEDs.
7. Test the lamp
Before hanging it over microgreens:
- turn the lamp on for a few minutes
- check if any LED is flickering or heating unevenly
- ensure the aluminum warms up slowly and evenly
- listen for any buzzing from the driver
If all looks good and every joint is insulated, the lamp works. This only shows that it lights up correctly, not that it is electrically safe: if you are not sure about the 230 V side, have it checked by a qualified electrician before you hang it over your trays.
8. Install it above your trays
Hang or mount the lamp:
- about 20-25 cm above microgreens for most varieties
- lower for fast-growing herbs
- higher for heat-sensitive crops
Hanging the lamp on chains or adjustable hooks lets you change the height as the crop grows. A 1 m lamp spans one row of microgreens trays on a 1 m shelf.
Even light = even growth.
6. No Soldering: A Shelf with Ready-Made LED Bars
The second way to light a microgreens shelf is a metal rack with ready-made LED bars. You lose the fun of building, but you get a closed light with an IP65 housing that you set up with a screwdriver.
Our full spectrum LED grow light is a 33 W bar, 900 mm long, with an IP65 housing for humid grow rooms. It runs on 100-277 V AC and plugs into a standard socket with a 140 cm cord. One connecting cable links up to 6 bars in a row, so up to 6 bars run from one socket. The bars come in packs of 2, 10 or 25, with mounting clips, screws and cables included.
For this setup you need a metal shelf, the bars (900 mm long), the clips and screws from the pack, the connecting cables (1, 2 or 5 in the packs of 2, 10 or 25), a timer and, if you want, chains. To set up the shelf, fix the bars under each level with the clips, connect them with the cable and plug the first bar into a timer. If you hang the bars on chains instead, you can raise them as the crop grows. If you add more bars later, you can buy an extra connecting cable.
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7. How Many Hours of Light Do Microgreens Need?
For our bars we recommend 14-18 hours of light a day. The University of Maryland Extension suggests about 16 hours a day and a light 6-12 inches (15-30 cm) above the foliage, depending on how strong it is. The Utah State University Extension keeps the lights on for 18 hours and off for 6.
Whatever lamp you use, plug it into a simple outlet timer. Microgreens need the same schedule every day, and a timer does it better than memory. During the first days after sowing the trays usually stay covered in the dark; we explain how long in our guide to germination and blackout days.
8. Safety & Practical Tips
- Always cut the power before working on any wires.
- No exposed connections: use heat-shrink on all electrical joints.
- The aluminum profile should be warm, not hot; improve airflow if necessary.
- A low-quality driver is the most common failure point; replace it if it flickers or overheats.
- Keep the driver away from water and condensation at all times.
- For a 1 m shelf, we recommend lamps in the 30-60 W range, depending on crop density and mounting height.
- Install the on/off switch on the 230 V input side, before the power supply.
These recommendations are based on practical experience and theory; you build and use this setup at your own risk.
DIY lamps are a good choice for small and medium growers who want reliable light they can build and repair themselves. It's the same method we used years ago in our own microgreens production, and those lamps still work today.
But we don't run a professional farm anymore, so treat this as a practical DIY solution you use at your own discretion.
When your light is ready, it is time for the first crop: for example White pea microgreens seeds, or, if you are starting professional batches, our Professional Microgreens Starting Kit.
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9. Share With Us
If you already use LED lamps for microgreens and found a model that works well, we would love to hear about it. Your experience can help other growers avoid problems.
We test new lamps all the time, so recommendations are welcome. If you have a setup worth checking, let us know. We're always open to learning from our growers.
FAQ
Can any LED light be used as a grow light?
Plants use most of the visible light, so a bright white LED can grow microgreens. What matters is enough light for long enough: we recommend 30-60 W per 1 m shelf, 14-18 hours a day. A weak decorative bulb will give you pale, leggy shoots.
How high should a DIY LED grow light hang above microgreens?
We hang our lamps about 20-25 cm above the microgreens; how close you can go depends on how strong the lamp is. Hang it lower for fast-growing herbs and higher for heat-sensitive crops, and check that the leaves do not get warm.
How many watts do I need for one shelf?
For a 1 m shelf we recommend 30-60 W, depending on how densely you sow and how high the lamp hangs. One DIY lamp with 30 one-watt LEDs or one 33 W ready-made bar is the lower end of that range.
Is a DIY LED grow light cheaper than buying one?
Usually not. The LEDs, driver and profile of a 30 W DIY lamp cost about €40-105 (October 2026). Our ready-made 33 W bar costs €43.05 per bar in a pack of 2 (€86.10) and less in larger packs, including VAT. You build a DIY lamp for control and repairability, not to save money.
Is a DIY LED lamp safe in a humid grow room?
A DIY lamp has no protection rating: its LEDs and joints are open, and a driver like the APC-35-350 is rated only IP42. Insulate every connection, keep the driver away from water and never spray the trays under the lamp. For a humid room, a closed IP65 bar is the safer choice.
Summary
A DIY LED grow light for microgreens is a 1 m aluminum profile with about 30 one-watt LEDs wired in series and a constant-current driver matched to the voltage of the chain. The parts cost about as much as a ready-made bar, so build it for control and repairability. If you simply need light over your trays, a ready-made IP65 bar on a timer is the simpler choice. Lamps, cables and everything else for a microgreens shelf are in our supplies for growing microgreens.
Sources and Further Reading:
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